Applying As Category G, Self Employed - Please Advise!

My husband is a classical musician and a dual US/UK citizen. As a soloist, he works by contract and hence not salaried. I am a US citizen and we are hoping to move our base to the UK.

My question is, in applying under category G (two years of self employment) he has earned, on average, over 18,600 a year. However, about half of that money was earned in the US. He paid US taxes on that income and UK taxes on what he earned in the UK and the EU. It is unclear to us if this is acceptable.

He already has several contracts in the coming year with major UK opera companies, so he would be able to prove on-going self employment.

I assume from the forms that my US income is not taken under consideration.